In the technology of display devices, the backlight module plays an important role. It generates a uniform luminance to present more crisp colors for a display panel. However, the backlight module generally is driven by high voltage. In the event that the current of the backlight module is not stable or maintains a saturated luminance for a long period of time, a scattering parasite capacitance effect occurs. This not only affects the entire luminance, the displaying picture of the display panel also fluctuates. This is not desirable to viewer's vision.
To remedy the problem of parasite capacitance, U.S. Pat. No. 6,798,151 discloses a technique to neutralize the leaking current and charges generated by parasite capacitance between the display device and the backlight module so that the phenomenon of unbalanced current flowing through lamp tubes caused by the leaking current is eliminated. And the light source of the lamp tubes can be maintained evenly to enable the display panel to get a uniform luminance in a wider range. That patent has an external metal mask on a display panel module to receive directly or through a linking element a signal, or a plastic middle layer in the external metal mask to receive the signal, thereby to eliminate, neutralize or offset the residual charges on the display panel.
But the aforesaid approach merely partly solves the problem. When the scattering parasite capacitance is generated, the display panel is already being interfered. And when the display luminance is saturated in normal conditions, the parasite capacitance exists almost constantly. Hence the aforesaid patent cannot neutralize or eliminate the parasite capacitance instantly. As a result, the picture quality suffers.